1. Field of the Invention
The present invention generally relates to footwear and, more particularly to footwear having shock attenuating members incorporated at the heel and forefoot thereof.
2. Prior Art
During the conduct of athletic activities such as running, basketball and tennis, substantial shock forces are imposed upon the user's foot. The shock forces are transmitted through the user's shoes to the user's foot each time the shoe comes in contact with the ground or surface over which the surface moves. Over time, the shock imposed upon the user can result in discomfort, fatigue and possible injury.
The terms "shock attenuation" and "energy absorption" are often used without delineating the difference. While both effects relate to the independent responses of a midsole's response to the force of impact, the term "impact response" more properly describes the response of a midsole to both effects. A desirable midsole, therefore, is one in which the impact response contains the appropriate balance of shock attenuation and energy absorption.
The prior art discloses a variety of shoe designs which employ cushioned soles to absorb at least a portion of the shock and thereby alleviate the problems. However, it has long been understood that the employment of cushioned soles must be as part of a structural environment which avoids destabilizing the user's foot while maintaining a firm platform for the user.
To attenuate force resulting from heel and forefoot contact, shoes were designed which focused attention upon cushioning. To this end, some designs disclosed by the prior art merely increase the thickness of the midsole. Other designs incorporate cushioning elements intended to provide enhanced cushioning effects. As an example, resilient, inflated bladders were used as midsole inserts. These designs do not resolve the major problem resulting from the shock produced by heel contact. The present invention resolves these problems through the use of cantilevered, shock attenuating members mounted at the heels of the shoe.
One of the shoe designs disclosed by the prior art employs replaceable, compressible shock absorbers at the heel and forefoot of the shoe. In this construction, the compressible members are replaceable. As a result, the shock absorbing members do not extend fully across the heel or forefoot. To the contrary, the shock absorbing members are disposed within receiving, aligned apertures in the midsole and outsole. The disadvantages of this design are the result of its inability to fully respond to the shock of heel and forefoot contact. The present invention resolves these problems by providing for cantilevered, shock attenuating members mounted across the full extent of the heel. The cantilevered members include opposing load alignment surfaces which stabilize the shoe by centering the load on heel contact and transferring peak loads to the periphery thereof.
Other designs disclosed by the prior art disclose compressible shock absorbing members at both the heel and forefoot of the shoe. However, the shoe constructions disclosed by the prior art exhibit substantially uniform impact response across the entire width of the heel and forefoot. This results in improper balance and stabilization of the force imposed on the shoe. This inadequacy is resolved by the present invention shoe construction.
The present invention substantially resolves the problems inherent in those designs disclosed in the prior art. The present invention employs shock attenuating members disposed at both the heel and forefoot of the shoe. The shock attenuating members disposed in the heel comprise a pair of cantilevered air chambers which are vertically secured with relationship to each other. The upper air chamber includes a load alignment surface aligned along the longitudinal axis of the heel. The lower shock attenuating member employs an equivalent load alignment surface in opposed relationship to that of the upper shock attenuating member. The impact response of the two cantilevered attenuating members centers the shock associated with heel contact while distributing or otherwise transferring peak loads along the periphery thereof.